Centrifugal decantation



W. MAUSS.

CENTRIFUGAL DECANTATION.

APPLICATION FILED FEB. 19. 1920.

1941 992850 Yatentd June 13, 1922.

W. Mam/5s.

UNHTEED WILHELM IVIA'USS, OF JOI-IANNESBUBG, TBANSVAAL, SOUTH AFRICA, ASSIGNOR '10 CONTINUOUS CENTRIFUGAL SEPARATORS LIMITED, 01? JOHANNESBURG, TRANS- VAAL, SOUTH AFRICA.

GENTRIFUGAL IDECAN'IATION.

arness.

Specification of Letters Patent.

Patented June 13, 1222.

To all whom it may concern:

Be it known that VILI-IELM MAUss, a subject of the King of Great Britain, residing at 69 Cullinan Buildings, Main and Simmonds Streets, Johannesburg, Transvaal Province of the Union of South Africa, has invented certain new and useful Improvements in Centrifugal Decantation, of which the following is a specification.

The present invention relates to centrifugal displacement separators for separating solids from liquids. It alsorelates to continuously rotating continuous separators in which the drum is opened periodically to discharge the settled solid.

A purpose of the invention is to provide a continuously acting centrifugal decanter suitable for treating large quantities of material of which the solid content constitutes a low percentage and is diflicult to settle. A particular material which the apparatus is designed to treat is the raw or prepared juice of cane or beet sugar in its diluted I state. This commonly contains not more than three or four per cent of solid matter, which is not much heavier than the juice.

A further purpose is to provide a ready means of indicating the progress of the separation so asto enable the separator to run for the maximum period and to fill as nearly as completely with settled solid, between each discharge, without danger of solid overflowing with the liquid.

The invention is illustrated in the accompanying drawing.

Fig. I is an elevation partly in section of the improved apparatus.

Fig. 11 is a plan of the timing mechanism.

The drum consists of a number of sections 1, 2, 3, 4, 5, splined on a shaft struc-,

ture 6, so as to be rotated together but to be capable of parting axially at the surfaces '7 by moving alon the shaft structure. The lowest section 1 does not move on the shaft and the uppermost section 5 is positively moved by several toggle devices, 8, 9 arranged symmetrically around-the drum. The intermediate sections 2, 3, 4 are separated by compression springs 10.

The drum shaft structure 6 is supported by the usual flexible bearing 11 and is rotated by a belt on the pulley 12. The drum closing toggle links 8, 9, are pivoted respectively to a part 6 of the shaft structure and to the uppermost drum section 5. From link 8 an arm 13 extends through a slot 14 in the shaft structure and is engaged by the grooved end 15 of a rod 16. Said rod is housed within the shaft structure 6 and rotates therewith, but reciprocates axially of the shaft to actuate the toggles. It is so reciprocated by a piston 17 having a hollow piston rod 18 through which the rod passes and to which it is connected by a bearing 19. The rod 16 is sufliciently flexible not to interfere with the usual swinging movement of the shaft structure in the bearing 11. The piston 17 is raised and lowered periodically in the cylinder 20 to effect the opening and closing of the drum, by pressure fluid distributed by the valve 21.

The drum sections provide a number of axially spaced separating chambers 22, 22 bounded by conical walls 23. When the sections are periodically parted, the settled solid is discharged, the walls 23 being sufiiciently inclined to permit such matter easily to slip from them. The toggle devices 8, 9, are designed to give a closing pressure greater than the axial component of the pressure of the material on the surfaces 23, which tends to force the drum sections apart.

Around the drum is a receiver 24 which receives the solid discharged from the chambers 22 and from which the solid is removed by a conveyor 25. There is also a receiver 26 in which the chamber 22 discharges and which passes the material to an open launder 27. By means of a three-way cook 28, the

. material from said launder can be sent to the receiver 24 or back to the source of supply by way of a pipe 29.

The mixture to be treated is supplied from a reservoir 30 and controlled by a tap 31; the. mixture being fed to the drum by a pipe 32. At the other end of the drum is an outlet 33 for the liquid, which outlet is at substantially the same radial distance as the peaks 34 between the chambers 22, 22 The liquid is caught in a receiver 35. At each of said peaks 34 and on the side of the same remote from the feed pipe 32 is a baflle 36 providing beneath it slot-s 37 leading to the next chamber.

In operation the drum is continuously rotated at high speed, a rotational speed of two thousand five hundred to three thousand revolutions per minute with a drum two feet in diameter being found suitable for the treatment-of dilute sugar juice. The mixture is :ted in from the pipe 32; and when the drum has become filled with mixture, the latterstands with its surface as indicated by the line 38. The liquid passes directly along the drum and is discharged continuously from the outlet 33. The solid settles in the chambers 22, filling first the lowermost of said chambers, then the upper ones in succession. Frothy matter which floats on the surface is held back by the battles 36 and is eventually discharged with the solid.

Upon the chambers 22 becoming filled with solid matter, such matter begins to deposit in chamber 22. Before said chamber 22 becomes filled, the feed is stopped by turning the cock Bl and the drum is discharged by separating the sections 1, 2, etc. The solid which is discharged into the receiver 24E is fully separated, whilst that which passes into the receiver 26 contains unseparated liquid. It can be examined as it flows in launder 2? and a determination made as to the completeness of the separation.

One of the dil'liculties of centrifugal decantation as compared with centrifugal filtration is that whereas in the latter the process oi? separation can be observed by watchin the l'lC uid eiiluent and the com aletion of separation is indicated by cessation of the flow, in the case oil decantation the separation goes on out of sight. There being no clear indication oil? the end point or the process there is a danger of either contaminating the el'lluent with over flowing solid or dis charging incompletely separated matter. The separately discharging end chamber 22 overcomes this di .culty since it is always discharged befor it is completely full. If there is any solid in it at all that fact shows that separation is complete in the other chambers, and it can without loss of economy be given sntficient capacity to provide ample margin for such variations in the rate oil deposition Oil solid as are likely to occur in practice. If this chamber regularly discharges material containing an undue quantity of liquid, the period between the discharges can be increased; whilst too great a proportion oi" solid would indicate danger of solid being passed away with the liquid, requiring the period to be reduced.

The destination of this material, i. e. to the general solid discharge 2 1- or to the pipe 29 for retreatinent, would obviously depend on the material being treated and on the con stancy of the product. It maybe observed that in most cases for which the apparatus is suitable the cost of returning the discharge from the last chamber is negligible; being in the case of a four chambered drum treating mixture with four per cent solid, one quarter of four per cent, i. e. one per cent,

' of the cost of treatin each char e.

This facility for ensuring properly separated products renders the separator particularly advantageous for automatic actuation. T 0 this end there is provided a time control consisting of a slowly and uniformly rotating drum 38. Said drum carries a pair 0t cleats 39, 39 which alternatelyengage pins and 46 of a tumbling bob a1 to throw the latter to one side or the other. The tumbling bob ll is connected by a rod ll to the tap 81, so that when the tumbling bob ll is thrown over to the left it opens the tap 31 and when thrown to the right it closes the same. 0n the same drum 38 are two other cleats 42, 1-2 adjustable in slots 43 which similarly engage the pins 18, 49 of another tumbling bob ll. The shaft 50 of the bob 1 1 carries a crank 51 which actuates the fluid distribution valve 21.

The cycle of operations is then as follows, the decanter drum being kept continuously rotating at working speed. As the drum 38 revolves the cleat 39 strikes the pin 4:6 of the tumbling bob 4t]. to open the tap 31 and mixture is fed to the drum, the separated liquid being continuously discharged to receiver Feeding is continued for a period proper to the mixture under treatment, for example twenty minutes. The second cleat 39 then engages the pin 45 of the tumbling bob ll to throw the latter over to the right whereby the supply cock 31 is closed and the discharge of liquid ceases. Immediately afterwards the cleat 4L2 strikes the pin 49 of the tumbling bob 44 and by throwing over the latter e'l'lects movement of the valve 21 to cause the drum sections to beparted, dis charging the whole contents of the drum into the respective receivers 21 and 26. This step occupies a few seconds, whereal ter tumbling bob set is thrown back by the cleat 12 engaging the pin 41:8 thereof and the valve 21 is reversed, cruising th drum to close thereupon cleat 89 strikes the pin 45 of the tumbling bob 4L1 causing the cock 31 to be opened and iccding of mixture to be resumed. The feeding period is determined experimentally,

after which it is only necessary occasionally to inspect the fl'luent in launder 27, and if necessary to adjust the period of rotation of the drum 38 and/or the position of the cleats 89 and 42 on said drum, in accordance with changes in the mixture, to maintain a predetermined standard of such effluent.

1. The process oil centrifugal deca'ntation which consists in centritugally treating a batch of mixture to cause deposition of solid and decantation of liquid therefrom, fully separating the bulk of said batch, and partially separating the last portion of the batch, discharging the decanted liquid, separately discharging the fully separated solid of the main portion, and separately discharging the partially separated solid of the last portion.

2. The process of centrifugal decantation which consists in centrifugally treating a batch of mixture to cause deposition of solid and decantation of liquid therefrom, fully separating the bulk of said batch, and partially separating the last portion of the batch, discharging the decanted liquid, separately discharging the fully separated solid of the main portion and separately discharging the partially separated solid of the last portion in a manner to permit its inspection.

3. The process of centrifugal decantation which consists in maintaining a separating drum in constant rotation, periodically supplying mixture thereto during a determined period, treating said mixture in the drum to cause deposition of solid and decantation of liquid therefrom, depositing solid during the last portion of the period separately from that deposited durin the first portion of the period, continuously discharging the decanted liquid, stopping the supply of mixture and thereafter discharging the solid deposited during the first portion of the period and simultaneously but separately discharging solid deposited during the last portion of the period.

a. In a centrifugal decanter, a drum arranged for decantation treatment of mixture, means to feed mixture thereto, a liquid overflow axially remote from the feeding means, a settlement chamber separate and axially spaced from the rest of the drum and next to the overflow, and means to discharge and collect material from the drum, said means maintaining the discharged solid contents of the separate settlement chamber separate from the other discharged solid contents of the drum.

5. In a centrifugal decanter, a drum comprising an axial series of settlement chambers, said drum being arranged for periodically opening said chambers to discharge their contents, means to feed mixture to one end of the drum, a liquid overflow at the other end of the drum and means for separately collecting material discharged from the chamber next to the overflow.

6. In a centrifugal decanter, a drum comprising an axial series of settlement chambers, said drum being arranged for periodically opening said chambers to discharge their contents, means to feed mixture to one end of the drum, a liquid overflow at the other end of the drum and means for separatelv collecting material discharged from the chamber next to the overflow, said means including an open channel in which such matter can be inspected.

7 In a centrifugal decanter, a drum comprising an axial series of settlement chambers, said drum being arranged for periodically opening said chambers to discharge their contents, means to feed mixture to one end of the drum, a liquid overflow at the other end of the drum and means for separately collecting material discharged from the chamber next to the overflow, said means including an open channel in which such matter can be inspected and means controlling the fiow of such material whereby it may be added to the main discharge from the drum or returned for retreatment.

8. The process of centrifugal decantation which consists in centrifugally treating a batch of mixture to cause deposition of solid and decantation of liquid therefrom, fully separating the main portion of said batch and only partially separating a small last portion of the batch and discharging the separated solid from each such portion separately.

9. The process of centrifugal decantation which consists in centrifugally treating a batch of mixture to cause deposition of solid and decantation of liquid therefrom, fully separating the main portion of said batch, only partially separating a small last portion of said batch and recovering the valuable constituent of said last portion by a further operation.

10. In a centrifugal decanter, a drum consisting of an axial series of ll-sectioned settlement chambers means to feed the material to the drum, a liquid overflow remote from the feed means, and a settlement chamber separate from the rest of the drum and next to the overflow and means to discharge solid material from the drum whilst the same is rotating.

11. In a centrifugal decanter, a drum composed of sections forming between them V- sectioned settlement chambers and axially separable to discharge solids from said chambers, means to feed material to the drum, and a liquid overflow remote from the feeding means,

In testimony whereof I aflix my signature.

WILHELM MAUSS. 

